One additional note...
Last fall when I was winterizing the GL1800, I was using the POS spark plug socket from the GL1800 toolkit rather than digging in my tool chest for a better socket. Well, I ended up cracking the ceramic body of one of the plugs.
It was a Sunday afternoon, and not many parts stores open. The only place I could find that had the plugs carried the BRK6E not the BRK6E-11. A quick look on the NGK site shows that the "dash" number is the gap (-11 for 1.1 mm). If there is NO "dash" number, then the gap is .8mm. That is the only difference between the two.
So, I bought the BRK6E re-gapped them to 1.0-1.1mm and all is fine.
Just wanted to toss in another data point in case the parts store hands you plugs that are labeled as BRK6E with no "dash" number.
08, Bright Red Metallic, ABS GL1800